During the coming year, we plan to feed guinea pigs an ascorbic-acid-free diet for two to six weeks to determine whether the intestinal absorptive capacity for this vitamin increases in pre-scorbutic and scorbutic states. Guinea pigs will also be maintained for two to four weeks on diets having five and 25 times the normal ascorbic acid content to determine whether the rate of intestinal absorption of this vitamin is reduced following high oral doses. The rate of absorption of ascorbic acid will be determined using 14C ascorbic acid by the in-vitro technique discussed in detail in the original grant proposal. Since ascorbic acid and dehydroascorbic acid both have anti-scorbutic properties, we plan to examine the transport properties of dehydroascorbic acid in small intestine similar to the manner used for ascorbic acid. Absorption will be studied in vitro with the influx technique. We will specifically test for saturation kinetics, metabolic dependence, sodium dependence ad competition with influx of ascorbic acid.